Low-water alarm



Jan. 3, 1928.

' H, w. C(ODDINGTON LOW WATER ALARM Filed Dec. 26. 1924 2 Sheets-SheetSum: 11* oz SW01 new H. W. CODDINGTON ,Jan. 3, 19

LOW WATER ALARM Fi led Dec. 26. 1924 2 Sheets-Sheet 2 4 Patented Jan. 3,1928.

untrue STATES HARRY W. COD'DINGTON, OF ROANOKE, VIRGINIA.

' LOW WATER ALARM.

Application filed December 26,1924. Serial No. 758,148.

This invention relates to low water alarms of the thermostatic type andhas among its objects to provide an improved device whereby theenginemen may be advised when the water in a steam boiler reaches adangerously low stage. A more specific object is to provide athermostatically operated low water alarm having a maximum operatingrange for a given change in temperature, also to provide a low wateralarm convenient to manufacture and easy to maintain in serviceablecondition. A still iurtlierobject is to provide a low water alarm espeially' adapted for use on locomotive boilers where the conditions ofservice are severe. With these general and other more specific objectsin view, the invention consists of the formation, combination andarrangement of parts as will be herein described and finally claimed.

In the accompanying drawings which show a preferred form. of theinvention,

Figure 1 is an organization view showing a low water alarm constructedin accordance with the principles of the "present invention. This figureshows the alarm in side elevational View and as attached to the shell ofan ordinarylocomotive boilersv Figure 2 is a fragmentary, longitudinal,"sectional view through the boiler end of the alarm. Figure 3 is afragmentary, transverse, sectional view through a portion of theopposite end of the alarm, this view being taken substantially on theline 3+3 of Figure 1. Figure iis a transverse, sectional view throughone end of the expansion element, the view being taken on the line H ofFigure 2. 'Figure 5 is a transverse horizontal sectional view throughthe boiler fitting of the device, this view being taken substantially onthe line 5 5 of Figure 2. Figure 6 is a transverse sectional view takenthrouglranother portion of the expansion element, this view being takensubstantially on the line (36 of Figure 1. Figures 7 and 8 arerespectively a transverse vertical sectional view and a fragmentary sideelevational view of the tube portion of the expansion element, theseviews showing a modified form of the bracketv which supports the fulcrum.rod. Figure 9 is a plan view sbowin' the upper portion of the boiler.titti which the expansion elementis attached. .The'scale of Figure l-issomewhat reduced over the scale of the re maining figures.

Before, proceeding with a description of the device as illustrated inthe drawings, it will first be mentioned that many difliculties andlimitations are met in the construction of thermostaticlow water alarms,particularly those intended for use onlocomotive boilers. Thedifferences in'temperature that are available and upon which operationdepends are small. Every means is resorted to in orde' to obtain anincrease in the thermal range, a gain of even a few degrees being soughtafter, and sometimes spelling the difference between a successful and anunsuccessful devioe. This will be better understood when it isremembered that a locomotive is exposed to a wide range ofclimaticconditions; is sometimes housed, again is exposed to rain or snow.Thedevice should be capable of being applied to and adjusted upon a coldboiler, not in moon that boiler over a wide range of steam pressures andcorresponding steam temperatures, whether the locomotive be standingtion, and must then be certain of-operation or running at high speed.The air temperaunmistakably to announce a condition of actual low water,it is of no less importance that it shall not soundfalse alarms as frommerely a surge that momentarily uncovers the tell tale portion of thedevice. Delicate thermal and mechanical problems are involved in theconstruction of any thermostatic low water alarm, where a limitedtemperature change and almost mlcroscopic. ex-

pansive movement must be utilized; andthe problems are, as statedfevengreaterv for losound from the stage of the water.

comotiveservice. The benefits derived from the various features of thepresent invention will be more clearly understood by having in mindthese peculiar operating conditions.

Referring now to the drawings the shell of the boiler is denoted by thenumeral 1.

At any suitable point, preferably ust above the point where itis desiredto indicate a critically low stage of water, the shell of the boiler isprovided with an opening 2, the upper or outermost portion of thisopening being beveled as indicated at 3. Seated from the exterioragainst this beveled portion of the opening is a ball faced ring atwhich is interiorily threaded, as indicated at 5, .and into which isscrewed a bushing 6. This bushing" may extend inward? y slightly withinthe steam cavity of the boiler, and is in turn interiorly threaded toaccommodate a threaded drop pipe 7 which is connectedthereto. Theexterior surfaceof the lower end of the bushing 6 formed with faces asindicated at 8 to accommodate the j awsof a wrench or other tool forscrewing "it firmly into the ring l from the under side of the latter.After screwing the drop pipe 7 into the bushing 6 the uppermost end ofthe pipe may be beaded over as indicated at 9 to prevent unscrewing, andthe pipe 7 may be welded to the bushing as indicated at lOto effectivelyseal the threaded connection and prevent the loss of the vacuum withinthecavity of'the alarm. The drop pipe 7 will be carried down to thelevel where it is desired that the alarm shall Mounted upon the uppersurface of the ring i is a special boiler fitting 11. A plurality ofstuds 14 are screwed into the shell of the boiler and the. upper ends ofthese studs extend through suitable openings in a bottom flange 15 ofthe fitting. The fitting 11 may, by means of the studs 14, be clampedfirmly against the ring at, the upper face of the ring t and the bottomface of the fitting 11 being machined to constitute a flatsteam tightjoint 12. lhe upper surface of. the ring l is also preferably providedwith a machined cylindrical extension 13 which is preferably arrangedconcentric with the bore of the ring t, this cylindrical. portioncomprising a dowel adapted to seat within a suitablyformed recess in thebase of the fitting 11. By the 1ntmJ-engagcment ot the said recess andthe dowel the fitting 11 is prevented from slippage with respect to thering at and the dowel and recess may also comprise a portion ofthe'steam tight joint between these two elements.

It has been found desirable to construct low water alarms of this typewith the drop pipe indirectly connected to the fitting 11 inthe mannershown, as the proper length of the drop pipe can be more accurately detemined and set than with co utruction other types. It has also been foundeasier to keep steam tight joints by this construction inasmuch as thering 4 may be made of one kind of material, the fitting 11 of anotherkind if desired, and the bushing 6 of still another kind of material. Ithas also been found easier to align the anxious parts in service'whenthe ring 4t is made separately from the fitting 11 as illustrated.

It has already been pointed out that the available movement of the freeend of the. expansion element is very small, being in clude the use onthe same of tools oflprecision in connection with the mounting of thealarm. A peculiar use and advantage of the construction just describedresides accordingly in the fact that the alarm may be thereby moreaccurately mounted upon the rough boiler, inasmuch asthe drop pipe unitand the fitting 11 may be adjusted with respect to each other and thejoint face'12-13 at. the ring 4 may be slightly angled by'aecuratemachine tools, so that by a slight rotation of the drop-pipe unit, theouter endof the mechanism may be brought into 'deiicate alignment,irrespective of boiler irregularh ties. r

The fitting 11 has a substantially cylindricatcavity 16 arranged invertical. alignment with the drop pipe! and in direct opencommunication, through the cavity of the drop pipe 7, with the steam orwater space of the boiler; This cavity extends upward for the fullheight of the fitting 11 and at the upper extremity is nrnrmally closedby means of a screw plug 17. Just below the top of the fitting thecavity 16 has a lateral branch '18 which is inciined sligl tly upwardfrom the horizontal, and to the outer end of this branch is connectedthe sloping expansion element 19. the cavity of the expansion elementbeing in open 'tluid conununication with the cavities 16'and 18. Theplug 1'7 i ll baffle 21.

of the same.

' nee 1,619 I 3 the connected cavities above the openings 22. Thisbaflle also serves to retard the fall of water from the expansionelement in cases where the lower end of the drop pipe is momentarilyuncovered, as by a surge of water in a locomotive boiler. Locatedslightly belowthe baffle 21 area plurality of inwardly extending stopsor shelves 23 formedupon the interior wall of the fitting 11. These areprovided in order toprevelnt the disk 21 from dro 'iping to a positionwhere the top of. the bushing. 6' might be blanked off in case the stem20 should break. It will be noted in Figure 5 that in the presentembodiment there are three of these shelves whereas there are but two ofthe openings 22. By making the number of shelves different from thenumber of openings,.the openings-can never simultaneously register withall'of the shelves and the disk will thereby be pre. vented from everdropping past the shelves whileat the same time the shelves can neverseriously interfere with the passage of steam and the slow passage ofwater through one or more of the openings 22.

It has been found by experiment that a battle arranged at the locationand in they manner just described is especially effective in preventingundue soundings'of the alarm from surges. Its e'liiciency in thisrespect is due to the fact that when the water attempts to drop backsuddenly through theopenings 22, a localized'vao'uum tends to form inthe space'immediately above the Also, under certain circumstances steambecomes trapped in the portion of the chamber 16 that lies above thebaffle 21, thus forming a seal for the waterin' the expansion element. ir i By integrally connecting the baffle 21 to the plug 17 it will beseen that when the plug is rotated in the unscrewing direction thebattle will. be similarly moved.

of the fitting, it 'will'be'broken loose from the same and propelledoutwardly through the incrustation by the rotatlon and retractionboilerend of the expansion element 19. For

this purpose this end of the fitting is bev eled as indicated as at .24.Themain portion of the expansion element is formed of a metallic tubewith a collar. 25-brazed or otherwise secured upon the outer peripheryThe endv of the tube is expanded aroundythe end of this collaras shown,at 26 and the metal of the tube. at the portion QS'lhGIGOf is thenmachined off to form, withthev bevel 24, a steam tight joint. Aspanriernut'27 is threaded upon the exterior surface of the branch of thefitting 1.1 and by means of thisfspanner nut fere" with the baffle.

7 Accordingly if the baffle should be scaled to the interior.

of three disks 29 which are substantially of the same diameter as theinterior of the cavity of the tube portion'of the expansion element.These dlsks are spaced somewhat fromelach other andare connected bymeans of suitable stein portions. Eachdisk is provided with an upper anda lower opening 30", these openings being designed and arranged topermit of the ready flow of steam to lill the cavity of the expansionelement but to retard the return of water from the cavity of theexpansion element to the boiler. It has been found preferable to rigidlyand permanently affix this bafliein the boiler end of the expansionelement. It has also been found permissible to do so inasmuch as it isnot necessary'to provide for means at the boiler end of the expansionelement to wash out andv cleanse the interior of the. tube as scale andsediment do notlodge within it to any great extent in ordinary usage. Itis accordingly preferable to mount these disks permanently in the lowerend of the expansion element and to furnish expansion elements fittedwith the baffles as a single man-. ufactured unit; This constructionalso permits of the use of the stem 20 to connect the baffle 21 to themain portion of the plug 17 as the presence, of the stem does not interIt has beenfound necessary. to occasionally wash out the drop pipe 7 andfor this reason the opening in the fitting. 11, normally closed by theplug 17, is maintained in alignment with they bore I of the tube 7. Whenthe plug 17 is un screwed, the baffle 21 which is connected theretobythe stem 20 iswithdrawn at the same time and direct access is had tothe cavity of the drop pipe 7.. I

It will be noted in Figure 9 that index figures. or match marks areprovided on the. top surface of the. plug 17 and onv the top edge of theadjacent'portion of the tilting 11. It is the intention thatthe plug 17shall be screwed into the fitting until the mark on the plug matcheswith the marks on the top of-the fitting. This'will insure the openings2210f the bafile 21 standing in a transverse direction with respect tothe line of the expansion element 19. At the same time, the baffle 28 isfixed in the tube portion of the expansion element in such manner thatthe openings 30 of the disks 29 will lie in vertical arrangement.Considering the channel of the vmember 11 and of the branch thereof, theholes 30 in the "upper disks are out of axial alignment with the holes22 ofthe disk 21 This arrangement still. further breaks up the localcirculation andciency has been found to be increased a greater amountthan by the addition of extra discs 29 to the bafli'e 28, as therlghtangled arrangement of battles breaks up the direct path ofcirculation of the water between the expansion element and the boiler,thereby resulting in a decreased temperature of the water within theexpansion tube. And by arranging the openings 22 out of axial alignmentwith the openings 30 a still greater difference in temperature isobtained and the range of the alarm very materially increased.

It should be understood that while the isolated water inthe expansiontube is sometimes referred to as being chilled, this expression isrelative only, for in fact the water in the expansion element under themost favorable conditions is many degrees higher in temperature than thesurrounding atmosphere and often not many degrees below the boilertemperature. The steam engineer is aware that the temperature of thewater inside of the boiler is the same as that of the steam itself. Thedrop pipe 7, being and between the several connected cavities of the lowwater alarm causes the isolated water in the expansion element to remainat a temperature closely approaching that of the steam unless means areintroduced to break up and hinder such circulation. The provision of thebafiie 21, and particularly the arrangement of the apertures 22 thereofwith respect to the apertures 30 in the discs of the baflle 28 has beenfound to be particularly effective in this respect, due to the fact thatthe water is compelled to follow a spiral course in its circulation andsets up cross currents in the space next above the battle 21. which tendto equalize the temperature of thc'water in this space, resulting in abreak up of the general thermic circula- 7 tion and causing a reductionin the temperature of the water in the expansion tube 19.

The outer end of the expansion element 19 comprises a terminal fitting31. A portion of this fitting at 32 has a square external contour andthis is arranged to rest in and to be supported by a jaw-shaped opening33 in a bracket 34. The bracket 34 is shown as attached to the'shell ofthe boiler by means of studs 35, with any suitable leveling means suchas melted babbitt poured into the crevice between the bracket and theshell of the boiler,this being indicated at 86. The ex pansion element19 is demountably' attached to the fitting 11 as heretofore explained,and

accordingly it may, when detached from the fitting 11., be lifted outofthe jaw-shaped opening of the bracket 34. In order to prevent undesiredlifting ofth'e outerend of the expansion element, either by hand orduring the operation of the devlce, a yoke member 35 is provided. Themember 35 1s attached to the bracket 34 by means of small bolts 36 andthe member-35 is arranged to embrace the outer end of the terminalfitting 31 as indicated in the drawings, to form an upper guide for thesame. The yoke must, of course, be removed from the bracket 34c beforethe expansion element can be lifted out of the jaw-shaped opening.Thefoutermost end of the fitting 31 may be, closed by a plug 37. A testpipe 38-witl1 a test valve-39 may be led out from the plug 37. The jawof the bracket 34 forms a means to prevent injury to the expansionelement when it is necessary to unscrew the plug 37. The main portion ofthe expansion element is usually formedof a relatively soft-mate rialsuch as a copper tube of relatively li ht gauge, and should the plug 37be ditiic ult to unscrew, the tube portion of the exp'an-- sion elementmight be injured except for the protection of the jaw engagement of theouter end of. the element with the bracket 34.

The yoke member 35 is provided in order to prevent undesired lifting ofthe outer end of the expansion element. It has been found that in theabsence of such guiding means a part of the available movement is lost,being expended in lifting of the outer end of lllll the expansionelement] The squared outer guide comprises means to prevent injury tothe tube 19 when the plug 37 is unscrewed. At the same time theremovable yoke member 35 makes it possible to readily'disassemble thedevice, and also conserves the available movement as heretoforementioned by direeting it in the desired direction. and preventingrising of the outer end of the expansion element. 7

Low water alarms of this type are actuated by thermal expansion andcontraction of the expansion element. As long as the open lower end ofthe drop pipe 7 is submerged the drop pipe itself, the fitting 11, thetube portion of the expansion element 19, and the terminal portion 31thereof will all be filled with water. This water is isolated from thewater of the boiler and with the introduction of the baffles near theboiler end of the expansion element as heretofore" described, localcirculation willbe practicali iy prevented, so that the water in theexpansion element will be at a considerably lower temperature than thewater within the boiler.

As soon as the. lower end of the drop pipe v 7 is uncovered, the waterin the'expansion element will tend to fall back into the boiler,"

and if the lower end remains uncovered for a short period of time thewater will all leave the expansion element and it will be replaced bysteam of a temperature corresponding to the boiler pressure. sionelement 19, and a portion ofthe fitting 11, will accordingly lengthen inresponse to the thermal change and, as the fitting 11 is rigidlyconnected to the boiler shell, whereas the outer end or" the expansionelement is free to slide longitudinally in the bracket 34, it will'beseen that the outer end of the expansion element will move in responseto the lengthening out the parts. This movement is taken advantage of toactuate an alarm lever which is pivot-ally attached to the terminalfitting 31 at 41. This feature of the device is not new, but in the pastit has been the practice to fulcrum the leversuch as l0 directly uponthe bracket 34:. :The result of this has been, that, considering thedevice to have been fitted up and adjusted with the boiler cold, whichis the usual practice, much of the expansive value of the expansion.ele-' ment has been lost, inasmuch as the shell of the boiler lengthenswhen the. boiler is fired up and theshell becomes heated. A feature orthe present invention is to overcome this defect and at the same time toincrease the range of the expansion element The general principleinvolved in correcting the defeet is to arrange a fulcrum for the lever.40 which will not be afi'ected by the expansion and contraction of theboiler shell. To do this for a boiler of the type shownit is desirableto carry the fulcrum back as near to the boiler end of the expansionelement 19 as practical. 'In the present embodiment, the fulcrum pointfor the lever is indicated at 4:2. Extending from the point 12 to thefitting 11 is a tie-rod 43 having a suitable jaw at the fulcrum end andbeingthreaded into a bracket 14 of the fitting 11 at the opposite end.Inasmuch as the fitting 11 is in efiect H a portion of the expansionelement, its expansion and contraction being efiective to actuate thelever 40, the same as though it were an integral part of the expansionelement, it will be seen that the fulcrum thus described is in effectlocated upon or-attached to the boilerend of the expansion element.v Therod 43 is preferably guided from the tube portion of theexpansionelement by means of a guide 45. This prevents vibration of the rod 43when the locomotive is in operation. It Wlll accordingly be seen thatwhereas the bracket 3 1 supports the outer end of the expansion element,the lever 40 is in turnsupported, not by the bracket 84, but'by theexpansion element through the connection 11,- and' that when the point41 moves to the left (see- Figure 1) in response to lengthening ofthe'partsthepoint 42' will not be similarly affected and the result willbe a downward movement of the extreme The expan-- 'filled with steam;

The pipe indicated at 52 beneath the whistle is for drainage purposesonly. When the water level is restored and the trapped'steam in theexpansion element. 19 and the con nected chambers has condensed, waterfrom the boiler will be drawn up into thevarious contract and the, lever10 will be retracted, permitting the valve 18 to closethereby shuttingoff the'alarm.

By means of the test valve 39 the device may be tested for completeoperation. By opening this valve for a few seconds the chilled waterwillbe blown out of the expansion element and connected parts and theconnected passageways will be filled with hot water from the boiler,which being at sub stantially the same temperature as the steam, theentire device will be actuated the same as though the passageways wereactually The pipe 38 preferably discharges into the ash pan. j

" In Figures 1 and 6 the guide for the rod 43-is shown as entirelysurrounding the tube of the expansion eleinent and brazed or otherwiserigidly secured thereto. In thebrazed orotherwise formed upon the-tube;

The ends or another suitable portion ofthe guide may contact with thisfeather to insure the guide be ng in proper position to receive the rodI have thus described a preferred form of my invention. Otherembodiments are contemplated, within the scope of the appended claims,without departing from thespirit' thereof. g

What is claimed is: 1. A low water alarm of. the thermostatic type, thesame including in combination with a steam boiler, a fitting attached tothe boiler, said fitting having a passageway therein, an. expansionelement in fluid communication with one'end of said. passageway, a droppipe connected to and infiuid communication with theother end of saidpassageway, the samebeinglarrangedin axial alignmentwith saidpassageway,.said drop pipe extending within the. steam; and waterconnected passageways. -As this isolated water cools the expansionelement will again space of the boiler and terminating in an I openlower end defining the critical stage I of the water, and a: baillearranged across the said passageway of the fitting, the battle lyingabove and in line with the said drop pipe. 7 a

2. A low water alarm of the thermostatic type, the same including incombination with a steam boiler a fitting attached to the boiler, saidfitting having a passageway therein, an expansion element in fluidcommunication with one end of said passageway, a drop pipe connected toand in fluid communication with the other end of said passageway, saiddrop pipe extending within the steam and water space of the boiler andterminating in an open lower-end defining the critical stage of thewater, a bafiie arrangedacross said pas-- sageway, the baflie lyingabove and in line with'the said drop pipe, a clean-out opening in thefitting above and in line with the baffle, and a member adapted tonormally close said opening, the baffle being attached to said closingmember. 7

3. A low water alarm of the thermostatic type, the same including incombination with a steam boiler a fitting attached to the boiler, saidfitting having a passageway therein, an expansion element in fluidcommunication with one end of said passageway, a droppipe connected toand in fluid communication with the other end of said passageway, saiddrop pipe extending within the steam and water space of the boiler andterminating in an open lower end defining the critical stage of thewater, a battle arranged across said passageway, the baffle lying aboveand in line with the said drop pipe, a cleanout opening in the fittingabove and in line with the baffle, a member adapt ed to normally closesaid opening, the bafile being attached to said closing member, andmeans'formed on the interior wall of the fitting comprising an emergencysupport for said baffle. I

4. A low water alarm of the thermostatic typeincluding, in combinationwith a boiler,

a boiler fitting having a cavity in fiuid commnnication with the steamand water space of the boiler, an expansion element connected to thefitting and extending laterally "therefrom, the same being in open fluidcommunication with the cavity of the fitting, a battle in the expansionelement near the'said fitting, and a bafiie in the cavity of thefitting, the said baffies being arranged in planes substantially atright angles to each other.

5. A low water alarm of the thermostatic type including, in combinationwith a boiler,

therein, some of the openings being arranged out of line, axially of thepassageway, with others thereof.

6. In a low water alarm of the thermostatic type, the combination with asteam boiler of a drop pipe adapted'to' extend within the steam andwater space thereof, a collar secured to the upper end of the drop pipe,the said collar being arranged to eo-ope erate with the boiler shell toform a steamtight joint, a fitting removably mounted upon the collar,and an expansionelement extending laterally from said fitting andremovably secured thereto, said fitting oomprising a fluid connectionbetween the drop pipe and the expansion element.

7. In a low water alarm of the thermostatic type, the combination with asteam boiler of a drop pipe adapted to extend within the steam and waterspace thereof, a collar secured to the upper end of the drop pipe, thesaid collar being arranged to cooperate with the boiler shellto form asteamtight joint, a fitting removably mounted upon the collar, anexpansion element extending laterally from said fitting and removablysecured thereto, said fitting comprising a fiuidconnection between thedrop pipe and the expan sion element, and means connected to the shellof the boiler adapted to clamp the said fitting to the collar and thecollar against the boiler.

8. A low water alarm of the thermostatic 1 type including in combinationwith a steam boiler a drop pipe extending from the exterior of theboiler into the steam space thereof and having an open lower enddefining the a removable baflie arranged across the cavity of saidhollow fitting above and in line with said drop pipe, and a normallyclosed cleanout opening in the fitting above and in line withthebafile.V p I ,7

9. A low water alarm of the thermostatic type including in combinationwith a boiler a fitting attached thereto,an expansion elementdemountablyattached to the fitting, a support bracket for the outer endof the expansionelement, the same having a recess formed therein adaptedto receive the expansion element, and a removable, member secured to thebracket and engaging the end of the expansion element, the walls of saidrecess and the said member being arranged to guide theexpansionelem-ent. r

' 10. A low water alarm of the thermostatic type including incombination witha boiler a fitting attached thereto, an expansion element demountably attached to'the' fitting, a V 7 support bracket for theouter end of'the expansion element, the same having a non-cirfluidcommunication with said hollow fitting, V

eular recess formed therein adapted to re-- pansion element being ofco-operating noncircular cross section, and removable means attached tothe bracket and overlying the expansion element, the same being adaptedto oo-operate with the outer end of the expansion element to hold thesame against rising 1 from normal position Within said recess.

In testimony whereof I aflix my signature.

HARRY W. CODDINGTON;

